Can you explain the transition of Sai from a 'Nirguni' to a 'Saguni' state as mentioned in the Satcharita?

Chapter 30 of the Sai Satcharita explains that Sai initially resides as the formless, or 'Nirguni.' However, it is through the devotion of His followers that He takes on a form with attributes, becoming 'Saguni.' The text poetically states, "In the beginning, You reside as the formless (Nirguni). Then, through the qualities of devotees' devotion, You draw the formless into form with attributes (Saguni)." This illustrates that the devotee's faith and love are the very means by which the formless divine manifests in a perceivable form to interact with them.